Crosshead assembly



April 4, 1967 F. F. CHELLIS 3,312,239

CROS SHEAD AS SEMBLY Filed June 17, 1964 '4 Shets-Sheet a F i g 3INVENTOR.

Fred F. Chellis Arforney April 4, 1967 F. F. CHELLIS 3,312,239

I v CROSSHEAD ASSEMBLY I Filed June 17, 1964 4 Sheets-Sheet 4 N M loINVENTOR. Fred F. Challis United States Patent chusetts Filed June 17,1964, Ser. No. 375,726

6 Claims. (Cl. 137-560) This invention relates to fluid regulatingapparatus and more particularly to apparatus which is capable ofcontrolling the flow of fluid into, within, and out of a refrigeratorwhere such control must be extremely accurate to insure eflicientperformance of the cycle on which the refrigerator operates.

There has recently been developed new basic refrigerator cycles whichdepend upon the introduction of a highpressure expansible fluid into arefrigerator, its transfer within the refrigerator for initial coolingby regeneration, and its subsequent expansion and further cooling withdischarge as low-pressure fluid from the refrigerator. The basic cycle,along with modifications and improvements, is described in detail inU.S. Patents 2,906,101, 2,966,- 035, 3,115,015, and 3,115,016, as wellas in copending application Ser. Nos. 280,577, now Patent No. 3,148,512,375,721, new Patent No. 3,218,815, and 375,854. These refrigeratorcycles and that portion of the apparatus in which the regenerativecooling and expansion takes place are not part of this invention. Theapparatus of this invention is rather an improved means for providingthe proper valving sequence and displacer motion for control of thefluid into, within, and out of the refrigeration apparatus; and it willbe understood that the apparatus of this invention (convenientlyreferred to as a crosshead assembly) can be adapted for use in theapparatus disclosed in the above-identified patents and copendingapplications. The crosshead assembly of this invention is, however,particularly suitable for use in controlling the fluid flow in arefrigerator described in copending application Ser. No. 375,721, and asan integral component of the cryogenic liquefier described in Ser. No.375,854, all of the applications referred to being assigned to the sameassignee as this application.

A number of devices are available which are capable of controlling theflow of fluid in two directions, but in general the greater the accuracyof control that is achieved, the more complicated becomes the apparatusfor doing it. Moreover, when it is necessary to add valving means and asynchronously timed means for moving a displacer, the prior artequipment becomes even more complicated and expensive to build. It wouldtherefore be desirable to have available apparatus which is capable ofachieving the type of fluid flow control required and which at the sametime is relatively simple to construct and extremely reliable in itsoperation. This latter quality of reliability becomes very importantwhen the crosshead is to be incorporated in a refrigerator or liquefierwhich is to be installed in equipment, such as spacecraft, required tooperate reliably over extended periods of time without maintenance.

It is therefore a primary object of this invention to provide anapparatus which is capable of accurately controlling the flow of fluidinto, within, and out of an enclosed space, the control incorporatingvalving means and means for moving a displacer. It is another objectiveof this invention to provide an apparatus of the character describedwhich is relatively'simple to build, and lends itself readily to fineadjustments both with respect to valve timing and displacer motion. Itis yet another object of this invention to provide apparatus of thecharacter described which may be incorporated into a refrigerator orliquefier which is required to operate over extended pcriods of timewithout maintenance. Other objects of the invention will in part beobvious and will in part be apparent hereinafter.

The invention accordingly comprises the features of construction,combinations of elements, and arrangement of parts which will beexemplified in the constructions hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

For a fuller understanding of the nature and objectives of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawings in which FIG. 1 is a sideelevational view of the crosshead assembly with the enclosing structureshown in crosssection;

FIG. 2 is a cross-section of the crosshead assembly taken along line 2-2of FIG. 1;

FIG. 3 is a cross-section of the crosshead assembly taken along line 33of FIG. 1;

FIG. 4 is a cross-section of the crosshead assembly taken along line4--4 of FIG. 1; and

FIG. 5 is a cross-section of a crosshead assembly taken along line 55 ofFIG. 4.

The crosshead assembly of this invention incorporates poppet valueswhich are driven in the proper sequence by unique adjustable camfollowers, and a Scotch yoke which is synchronized with the valveoperation for imparting the proper up and down motion to a displacerwithin the refrigerator, this motion achieving the desired fluid flowcontrol within the refrigerator.

FIG. 1 illustrates the general arrangement of the crosshead assemblycomponents. This assembly will be seen to comprise a crankcase housing10 mounted in fluid tight relationship on a crankcase block 11 which inturn is mountedthrough suitable sealing means to make a fluid-tightconnection with a refrigerator support 12 and the cylindrical wall 13 ofthe refrigerator itself. Within the refrigerator a displacer 14 (only afragment of which is shown) moves up and down to define within theenclosure two or more fluid volumes one of which is shown as the upperwarm volume 15. The remaining portion of the refrigerator is notillustrated here since it isnot part of the invention and referenceshould be had to copending application Ser. No. 375,721, whichillustrates a typical refrigerator for which this crosshead assembly issuitable.

Movement of the displacer and of the valves is accomplished by means ofan electrical motor (not shown) which is located within motor housing16, which in turn is afiixed to the crankcase housing 10 and made fluid-V tight through the use of a front plate 17 and a back plate 18 held inposition by bolts 19. Thus the assembly as illustrated in FIG. 1 isfluid-tight for reasons which will be explained subsequently. Thedisplacer 14 is given suitable up and down motion through a suitableconnection between motor shaft 21 and displacer rod 22 acting through abearing 23 which is positioned in a Scotch yoke 24. The details of thisdriving mechanism will be described in detail in connection with FIGS. 2and 3.

The required motion is imparted to poppet valves through the up and downmotion of an inlet valve cam follower 26 which is driven by inlet cambearing 27 and a discharge valve cam follower 28 which is driven by adischarge cam bearing 29. The crankcase 32 is sealed in front by meansof a plastic window assembly 33 and suitable sealing ring 34. Thisplastic window assembly can be moved back and forth and rotated, forpurposes described below, by means of a knurled piece 35.

The mechanism by which the displacer is moved up and down in propersequence is illustrated in detail in FIGS. 2 and 3. FIG. 2 illustratesthe relationship between the motor shaft 21 and the auxiliary shaftassociated with the Scotch yoke bearing. Attached to motor shaft 21 is acollar 49 which is made integral with an auxiliary off-center shaft 41.The bearing 23 which drives the Scotch yoke 24 is mounted on thisauxiliary shaft 41. Mounted on collar 49 is a second collar 42 and theentire collar assembly is permanently fixed to the motor shaft throughthe use of a key pin 43. The collar assembly rotates in a back plate 44which completes the crankshaft enclosure. Finally, it will be seen inFIG. 2 that the bearing 27 associated with the inlet valve is mounted oncollar 40 and the bearing 29 which is associated with the dischargevalve is mounted on collar 42. These bearings are mounted slightlyeccentric to each as is apparent from FIG. 1.

Turning now to FIG. 3 it will be seen that rod 22 is mechanicallyaffixed to displacer 14 through a suitable means such as pin 45. Itmoves within a block 11 through a bushing 46 and a seal housing 47 whichhas associated with it sealing rings 48 and 49. There must of course becomplete fluid isolation between chamber in the refrigerator and thecrankcase 32 of the crosshead assembly inasmuch as all fluid flow mustbe controlled through valve means. The upper extension of rod 22 hasassociated with it a bushing 50. It r'ecipr'ocates within an enclosedvolume 52 which is defined by an extension 53 of the crankcase housing.This extension is in turn made fluid-tight through the use of suitablescrew 54 with sealing rings 55. Bushing 50 has a flattened area on itsoutside surface to insure free fluid flow around the bushing 50 intochamber 52 so that at no time will there be a pressure differentialbetween 32 and 52. Finally, the Scotch yoke 24 has on one side a groove56, the purpose of which is to engage a pin 57, mounted in housing 10,to prevent any rotational movement of the yoke or the rod. Movement ofthe rod 22 and of the cam followers 26 and 28 may be effected externallyby forcing the plastic window assembly 33 (FIG. 2) inwardly until shaft41 is engaged in a recess 58 in the plastic window assembly. By turningthe knurled piece 35 it is ossible to rotate the shafts 41 and 21 thusachieving external adjustments.

The manner in which the high-pressure fluid is introduced into andlow-pressure fluid is withdrawn from chamber 15 through the poppetvalves is illustrated in detail in FIGS. 4 and 5. However, beforedescribing the apparatus in detail it will be helpful to trace the fluidflow path. High-pressure fluid is brought in by line 60 through conduit61 and its flow controlled by high-pressure valve 62. The high-pressurefluid passing through valve 62 enters chamber 15 by way of conduit 63.The low-pressure fluid which is to be discharged from the refrigeratorby way of chamber 15 passes first through conduit 64, then throughlow-pressure valve 65 and finally 7 through conduit 66 to enter thecrankcase interior 32.

Thus it will be apparent why the crankcase must be fluid tight since itis an integral part of the fluid flow path. From crankcase 32 the fluidflows through ports 67 (one of which is shown) into the motor housing 16and then by way of conduit 68 (FIG. 1)'to the compressor where it iscompressed prior to its recycling by way of conduit '60 into therefrigerator. In passing through motor housing 16, the low-pressurefluid cools the motor.

FIG. 4 illustrates the high-pressure valve in detail. Inasmuch as thelow-pressure valve 65 is identical with the high-pressure valve 62, onlyone valve system need be described. Valve block 72 is sealed into thecrankcase block 11 through the use of sealing rings 73, 74, and 75. Themain valve body 76 is actuated downwardly by valve rod 77. It extendsinto a fluid volume 78 and is normally held in the closed position shownin FIG. 4 by means of a spring 79 which extends into a recess 80 andacts on valve body 76 to force it upwardly. When the valve body is inits lower position by reason of force applied through valve rod 77,fluid flows upwardly into volume 82 and then in o conduit 63 throughpassage 83.

In a similar manner low-pressure fluid flows upwardly through conduit 64through low-pressure valve 65, which is similarly actuated, and then byway of conduit 66 out of the refrigerator.

The actuation of the valve rods 77 is achieved by two cam followers, theone for the inlet valve being designated by numeral 26, and the one forthe discharge valve by numeral 28 (see FIG. 5). As in the case of thevalves these actuation mechanisms are identical and need be described indetail for the inlet valve only. The cam follower 26 is in effect arocker arm formed of an upper prong 88 and a lower prong 89 which definebetween them at one end a gap of varying cross-section, and which areintegral at the other end. Movable within this gap of varyingcross-section is an adjusting pin 90 which is attached to a horizontalrod 91 which in turn may be moved back and forth by means of screw 92 toincrease or decrease the distance between prongs 88 and 89. Hence themovement of rod 91 is used to adjust the degree of displacement of valverod 77. This achieves an extremely fine degree of adjustment which isimportant in a device such as this. The cam follower 26 is mounted on asuitable pivot pin 93 and is given its downward motion to open the valveby contact with the surface of bearing 27.

Finally FIG. 4 illustrates the means by which the crankcase block can beconveniently attached to the refrigerator support plate 12 through theuse of suitable keyed pieces 97 which engage a groove 98 in the block 11and which are held in place by means of screws 99.

It will be seen from the above description of the crosshead assembly ofthis invention that it is possible to synchronize the movement of theinlet and discharge valves with the movement of the displacers withinthe refrigerator so that high-pressure fluid is admitted while thedisplacer is moving upwardly and dwelling in an uppermost position andto open the discharge valve while the displacer is moving downwardly andremaining in its lowermost position. It Will be appreciated that this isa very general and simplified statement of the desired fluid flowpattern which must be accomplished in a refrigeration cycle such as thatdisclosed in US. Patent 2,966,035. It is of course within the scope ofthis invention to adjust the movements of the valves and the displacerrod to achieve any desired fluid flow pattern. A further examination ofthe description and drawings will show that the crosshead assembly ofthis invention achieves the required fluid flow into, within, and out ofa refrigerator with a relatively simple apparatus. However, accuracy ofadjustment and control and reliability of operation are not sacrificedin the achievement of this simplicity.

It will thus be seen that the objects set forth above among those madeapparent from the preceding description are efficiently attained andsince certain changes may be made in the above construction withoutdeparting from the scope of the invention it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

I claim:

1. A crosshead assembly capable of controlling the flow of a fluid intoand out of an enclosure and of controlling the circulation of said fluidwithin said enclosure through the motion of a member movable within saidenclosure, comprising in combination '(a) motor means adapted to rotatea motor shaft;

(b) a motor housing;

(0) la crankcase block aflixed in fluid-tight relationship to saidenclosure;

(d) a crankcase housing forming withsaid motor housing and saidcrankcase block a fluid-tight crankcase;

(e) fluid conduit means adapted to conduct high-pressure fluid into andlow-pressure fluid out of said enclosure;

(f) mechanically actuated high-pressure inlet :and lowpressure exhaustfluid control valves associated with said fluid conduit means, locatedwithin said crankcase block and adapted to control the flow of saidhigh-pressure and said w-pressure fluid;

(g) a driving rod associated with said movable member in said enclosureand extending through said crankcase block into said crankcase;

(h) an auxiliary shaft aflixed to said motor shaft, through first collarmeans, and eccentrically mounted thereto;

(i) second collar means mounted on said motor shaft adjacent to saidfirst collar means and eccentric thereto;

(j) driving rod moving means within said crankcase and comprising aScotch yoke and an associated hearing cam mounted on said auxiliaryshaft;

(k) inlet valve actuating means affixed to said first collar means andeccentrically mounted thereto; and

(1) outlet valve actuating means affixed to said second collar means.

2. A crosshead assembly in accordance with claim 1 wherein said fluidconduit means comprises (1) a high-pressure conduit communicatingbetween an external source of said high-pressure fluid and saidenclosure by way of said high-pressure inlet fluid control valve, and

(2) a low-pressure path communicating between external discharge meansand said enclosure, said path comprising in combination saidlow-pressure exhaust fluid control valve, said crankcase, and said motorhousing, whereby said motor is located in said fluid path and is cooledby said low-pressure fluid.

3. A crosshead assembly in accordance with claim 1 wherein each of saidfluid control valves is a poppet valve having spring means associatedtherewith adapted to apply a positive force thereto, said force being inopposition to force applied by said valve actuating means associatedtherewith.

4. A crosshead assembly in accordance with claim 3 wherein each of saidpoppet valves has a valve rod extending into said crankcase; and saidvalve actuating means comprises (1) a rocker arm engaging said valve inforce-applying relationship, and

(2) a bearing cam mounted on its associated collar means and adapted toapply force to said rocker arm over those periods when said valves areto be opened.

5. A crosshead assembly in accordance with claim 4 wherein said rockerarm comprises two prongs and means for adjusting the distance betweensaid prongs whereby the displacement of said valve rod may be adjusted.

6. A crosshead assembly in accordance with claim 1 wherein saidcrankcase housing has as a portion of one side a circular transparentplastic assembly having in its inner surface a recess adapted to engagethe end of said auxiliary shaft and being rotatable and movable inwardlythereby to engage said end of said auxiliary shaft whereby said shaftmay be turned for adjustment by a force external of said crankcase.

References Cited by the Examiner UNITED STATES PATENTS 2,966,034 12/1960Gifford 626 2,979,917 4/1961 Meagher 62508 M. CARY NELSON, PrimaryExaminer.

W. R. CLINE, Assistant Examiner.

1. A CROSSHEAD ASSEMBLY CAPABLE OF CONTROLLING THE FLOW OF A FLUID INTOAND OUT OF AN ENCLOSURE AND OF CONTROLLING THE CIRCULATION OF SAID FLUIDWITHIN SAID ENCLOSURE THROUGH THE MOTION OF A MEMBER MOVABLE WITHIN SAIDENCLOSURE, COMPRISING IN COMBINATION (A) MOTOR MEANS ADAPTED TO ROTATE AMOTOR SHAFT; (B) A MOTOR HOUSING; (C) A CRANKCASE BLOCK AFFIXED INFLUID-TIGHT RELATIONSHIP TO SAID ENCLOSURE; (D) A CRANKCASE HOUSINGFORMING WITH SAID MOTOR HOUSING AND SAID CRANKCASE BLOCK A FLUID-TIGHTCRANKCASE; (E) FLUID CONDUIT MEANS ADAPTED TO CONDUCT HIGH-PRESSUREFLUID INTO AND LOW-PRESSURE FLUID OUT OF SAID ENCLOSURE; (F)MECHANICALLY ACTUATED HIGH-PRESSURE INLET AND LOWPRESSURE EXHAUST FLUIDCONTROL VALVES ASSOCIATED WITH SAID FLUID CONDUIT MEANS, LOCATED WITHINSAID CRANKCASE BLOCK AND ADAPTED TO CONTROL THE FLOW OF SAIDHIGH-PRESSURE AND SAID LOW-PRESSURE FLUID; (G) A DRIVING ROD ASSOCIATEDWITH SAID MOVABLE MEMBER IN SAID ENCLOSURE AND EXTENDING THROUGH SAIDCRANKCASE BLOCK INTO SAID CRANKCASE; (H) AN AUXILIARY SHAFT AFFIXED TOSAID MOTOR SHAFT, THROUGH FIRST COLLAR MEANS, AND ECCENTRICALLY MOUNTEDTHERETO; (I) SECOND COLLAR MEANS MOUNTED ON SAID MOTOR SHAFT ADJACENT TOSAID FIRST COLLAR MEANS AND ECCENTRIC THERETO; (J) DRIVING ROD MOVINGMEANS WITHIN SAID CRANKCASE AND COMPRISING A SCOTCH YOKE AND ANASSOCIATED BEARING CAM MOUNTED ON SAID AUXILIARY SHAFT; (K) INLET VALVEACTUATING MEANS AFFIXED TO SAID FIRST COLLAR MEANS AND ECCENTRICALLYMOUNTED THERETO; AND (L) OUTLET VALVE ACTUATING MEANS AFFIXED TO SAIDSECOND COLLAR MEANS.